Did anyone go through a threatened miscarriage but didn't miscarry?

I have been bleeding for a couple days, very light, not even enough to fill a pad. I have some minor cramping that feels like premenstral cramps. Yesterday I went to the ER, the cervix is totally closed, and on a sonogram they found the baby with a heartbeat! The OB said she felt positive about the outcome, while the ER doctor was still concerned. I go in tomorrow for blood test to see if the hormone levels are rising. I am terrified right now. Everytime I go to the bathroom I scrutinize the small amount of blood. Is it changing from pink to red? Is there more? Is that a clot? I am going crazy with these questions. I know I can't do anything to stop a miscarriage, but I would love to know if anyone went through this and the outcome was positive. Thanks.